Yes it is when a player is roughing

Judging Amy - 1999 Unnecessary Roughness 2-5 is rated/received certificates of:

Argentina:13

If a player PURPOSEFULLY hits another player after the whistle or when the play is done.

Yes, in a 1974 game againt the Minnesota Vikings, Csonka was called for an unnecessary roughness pentalty while running the football.

Yes there has.

Larry Csonka received a personal foul for unnecessary roughness while running the ball. The Miami Dolphins were playing the Buffalo Bills. Saftey John Pitts was the defensive player who took the blow issued by Csonka's right fist.